diff --git a/internals/zendapi/intro.xml b/internals/zendapi/intro.xml
index 9f7dd0d143..0d15e8f66c 100644
--- a/internals/zendapi/intro.xml
+++ b/internals/zendapi/intro.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="ISO-8859-1" ?>
- <!-- $Revision: 1.1 $ -->
+ <!-- $Revision: 1.2 $ -->
 <sect1 id="zend.intro">
  <title>Introduction</title>
  <abstract>
@@ -20,6 +20,19 @@
   As soon as this point is reached, it's time to touch the heart of PHP
   and take a look at its core, the C code that makes PHP go.
  </para>
+ <warning>
+  <para>
+   This information is currently rather outdated,
+   parts of it only cover early stages of the ZendEngine 1.0 API
+   as it was used in early versions of PHP 4.
+  </para>
+  <para>
+   More recent information may be found in the various README files that
+   come with the PHP source and the 
+   <ulink url="&url.zend.internals;">Internals"</ulink>
+   section on the Zend website.
+  </para>
+ </warning>
 </sect1> 
 <!-- Keep this comment at the end of the file
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